The present invention relates to an image forming device that employs an electrophotographic method using developers of a plurality of colors and, in particular, to an image forming device that detects color densities to perform color correction process.
It is known in the art for a color laser printer to detect the densities of different colors and perform color correction based on the detection results (for example, Japanese Patent Application Publication No. 2001-201904).
A typical color laser printer uses a method known as the four-cycle printing method, wherein a multicolor image is formed on an image-support member by four rotations of a photoconductor such that a monochromatic toner image is formed at each rotation of the photoconductor, and then the multicolor image on the image support member is transferred to a recording medium. When performing the density detection for each color in this printer, the photoconductor rotates four times in the same manner as during printing. Therefore, the density detection necessitates at least four rotations of the photoconductor, which takes too long a time.
In this four-cycle printing type of laser color printer, or in a tandem-style color laser printer in which one photoconductor is provided for each color, all of the toner used during density detection is discarded, which is a waste.
These problems are not limited to color laser printers, but occur in other image forming devices also.